With the increasing demands on peak power consumption, ice storage is an environmentally benign method that has been utilized to shift air conditioning power loads to off-peak times and rates. A need exists not only for load shifting from peak to off-peak periods, but also for increases in air conditioning unit capacity and efficiency. Current air conditioning units having energy storage systems have had limited success due to several deficiencies including reliance on water chillers, that are practical only in large commercial buildings, and have difficulty achieving high-efficiency. In order to commercialize advantages of thermal energy storage in large and small commercial buildings, thermal energy storage systems must have minimal manufacturing and engineering costs, maintain maximum efficiency under varying operating conditions, demonstrate simplicity in the refrigerant management design, and maintain flexibility in multiple refrigeration or air conditioning applications.
Systems for providing stored energy have been previously contemplated in U.S. Pat. Nos. 4,735,064, and 4,916,916 both issued to Harry Fischer and to U.S. Pat. No. 5,647,225 issued to Fischer et al. All of these patents utilize ice storage to shift air conditioning loads from on-peak to off-peak electric rates to provide economic justification and are hereby specifically incorporated by reference for all they teach and disclose.